\begin{table}[htbp]\centering
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\caption{Electoral System, Candidate Communication, and Change in Partisan Affect (Feeling Thermometer)\label{tab:apfthetero}}
\begin{tabular}{l*{3}{c}}
\hline\hline
                &\multicolumn{1}{c}{(1)}   &\multicolumn{1}{c}{(2)}   &\multicolumn{1}{c}{(3)}   \\
                &Affective Polarization   & In-Group   &Out-Group   \\
                &     b/se   &     b/se   &     b/se   \\
\hline
RCV Compliment  &   -0.008   &   -0.015   &    0.002   \\
                &  (0.008)   &  (0.010)   &  (0.010)   \\
RCV Comp. + Endorse&   -0.006   &   -0.011   &   -0.000   \\
                &  (0.008)   &  (0.010)   &  (0.010)   \\
Conservativism  &   -0.002   &   -0.001   &    0.002   \\
                &  (0.001)   &  (0.002)   &  (0.002)   \\
RCV Compliment x Conservativism&    0.000   &    0.001   &    0.000   \\
                &  (0.002)   &  (0.002)   &  (0.002)   \\
RCV Comp. + Endorse x Conservativism&   -0.001   &    0.001   &    0.002   \\
                &  (0.002)   &  (0.002)   &  (0.002)   \\
Constant        &    0.004   &    0.011   &    0.003   \\
                &  (0.005)   &  (0.007)   &  (0.007)   \\
\hline
R$^2$           &     0.01   &     0.00   &     0.01   \\
\textit{N}      &     2250   &     2250   &     2250   \\
\hline\hline
\end{tabular}
\end{table}
